databases.  Zones with a nonpersistent database and no 'file' option will get
an error logged at load time.

lines under 80 columns

and dns_zone_getdatabase() to dns_zone_getfile(), with the idea that
they (and the 'file' zone option) will always refer to the zone's
master file, regardless of the database implementation.  If a
non-rbt database uses a disk file for its internal storage, the
name of that file should be specified as an argument to the 'database'
option, not using the 'file' option.

should eventually be configurable at runtime, or at least with a
configure option, but now it's just a #define in rbt.h.

algorithmically in Tcl code

stdout.

unexpected error [RT #215]

                        assertion failure. [RT #302]

 566.   [func]          New public function dns_timer_setidle().

string token would fail.

registered dynamically.  Simple database drivers no longer use the
keyword "simple" in named.conf - the driver name is sufficient.

insert its definition before the #undef, not after it.  Instead, rename
L_SEARCH to L_SEARCHLIST